Clinical concern about the nature of focal masses in the breast, liver, kidney, adrenal and pancreas commonly result in biopsy or surgery for diagnosis. This project proposes the noinvasive characterization of the nature of these masses which may preclude the need for further concern or may expedite therapy. Doppler techniques will be used to demonstrate the presence of neovascularity which occurs at the growing edge of many malignant tumors. For breast masses, a 9 MHz CW Doppler probe will be utilized. Tumor signals will be elicited from the periphery of any palpable mass or from an impalpable abnormality localized by mammography. We will also evaluate the application of color Doppler to facilitate the recognition of arterio-venous shunts. The peak systolic Doppler shift frequency around the tumor will be compared to that in the mirror-image position of the contralateral breast. We will establish the cut-off frequency difference to optimize the sensitivity and specificity for differentiating benign from malignant tumors. We will also correlate the presence of tumor signals with known predictors of prognosis. Using the pulsed Doppler technique at 3 MHz we will examine all focal liver lesions comparing peak systolic frequencies found in benign all malignant masses. Preliminary data indicate that arterio-portal shunting in hepatomas allows their specific recognition because of the presence of very high velocity jets. We will also evaluate the possible application of color Doppler for this application. Focal masses of the kidney, adrenal and pancreas will be characterized by pulsed, and color Doppler. Comparison of the peak-systolic and end-diastolic frequencies will be made. The sensitivity and specificity of the technique will be established for the prediction of malignancy. More elaborate signal processing will be performed using principle component analysis to search for other parameters capable of enhancing the differentiation of tumors.